Looks at my own monitoring of my system. So just base OS, rainmeter, Skype, email monitor, Nvidia app, one drive and drop box, running VLC music and having about 30 webpages open I am eating atm 6.2GB of RAM. If you MULTITASK alot it is easy to go OVER 8 GB, what I just said is 'A typical' of most 'teenagers' these days, they multitaks, for those older then I (and I am 47) they can't understand how anyone goes over 4GB, since they aren't running Windows 7 Aero, don't look at email except when they want to, don't run Skype all the time, don't etc. etc. etc.
So it all depends WHAT you do that matters for the amount of RAM you need.